Fluoroelastomer compositions

ABSTRACT

Fluoropolymers comprising a fluoroelastomer matrix incorporating therein particles of a semicrystalline fluoropolymer formed of tetrafluoroethylene (TFE) homopolymers or copolymers, wherein the average particle sizes of the semicrystalline fluoropolymer latex range from 10 to 100 nm.

[0001] The present invention relates to fluoropolymers essentiallyformed by a mixture of a fluoroelastomer and a semicrystallinefluoropolymer usable for sealing manufactured articles in theelectronic, optical and pharmaceutical industry.

[0002] More specifically the present invention relates to fluoropolymersformed by a mixture of a fluoroelastomer and a semicrystallinefluoropolymer, characterized by improved mechanical properties combinedwith good properties of elastic retention (lower compression set) andvery good surface appearance without roughness. It is well known thatone of the fluoroelastomer uses is the preparation of O-rings for seals:for this application it is essential that the O-ring surface is smooth.

[0003] The use of fluoroelastomers containing polytetrafluoroethylene(PTFE) particles to improve the properties of abrasion-resistance and ofhot tearing the obtained manufactured articles is known in the priorart. As described in Japanese patent 57-107,336, the fluoroelastomerabrasion-resistance is improved by physically mixing solid curablefluoroelastomers with PTFE powders having a low molecular weight, in therange 500-200,000 as average molecular weight by number (M_(n)). SaidPTFE is prepared by thermal decomposition at a temperature between 450°C. and 600° C. for prolonged times or by irradiation with ionicradiation of high molecular weight PTFE. An alternative method forobtaining PTFE having a low molecular weight is that to polymerize TFEin the presence of chain transfer agents. The fluoroelastomer and thePTFE powders are mixed in Banbury or in calender.

[0004] In U.S. Pat. No. 4,879,362 and U.S. Pat. No. 4,904,726 mixturesof fluoroelastomers with resins of PTFE modified with the addition ofcomonomers such as hexafluoropropene (HFP), perfluoropropylvinylether(PPVE), etc., are used, in order to avoid PTFE fibrillation problemswithout losing the reinforcement properties that the PTFE gives to theobtained fluoroelastomers. The comonomer results much more present onthe polymeric particle surface, so as to allow an uniform distributionin the fluoroelastomer without the formation of visible agglomerates.The latter should be the cause of fibrillation phenomena.

[0005] In EP 708,797 fluoroelastomer compositions formed by afluoroelastomer and by a semicrystalline fluorinated filler in the formof micropowder which are obtained in curing compounds not containingmetal species, are described. Said compositions give a low release ofmetal species under conditions where an high purity is required, butthey show poor mechanical properties. Tests carried out by the Applicant(see the comparative Examples), have shown that the surface of themanufactured articles obtained from said fluoroelastomer compositionsshows roughness. It is well known that in the O-ring preparation,typical fluoroelastomer application, surfaces having a low roughness inorder to obtain good sealing properties, are required. Thesemicrystalline fluorinated filler is based on PTFE or PTFE modifiedwith a comonomer and obtained by emulsion or suspension polymerization.The high molecular weight PTFE is subjected to irradiation, as abovesaid, in order to reduce the molecular weight. This makes easier thePTFE milling produced by a suspension process; it eliminates thefibrillation and reduces the PTFE agglomeration obtained by an emulsionprocess.

[0006] The need was felt to have available fluoroelastomer compositionscomprising a semicrystalline fluorinated filler having improvedproperties compared with those of the prior art and specifically withthe following property combination:

[0007] improved mechanical properties

[0008] good elastic retention properties (lower compression set—verygood seal)

[0009] very good surface appearance roughness free.

[0010] The Applicant has unexpectedly and surprisingly found that it ispossible to obtain the combination of the above mentioned properties, byincorporating in the fluoroelastomer matrix PTFE particles or itscopolymers having well defined sizes as specified hereinafter.

[0011] It is therefore an object of the present invention fluoropolymerscomprising a fluoroelastomer matrix incorporating therein particles of asemicrystalline fluoropolymer latex formed by tetrafluoroethylene (TFE)homopolymers, or TFE copolymers with one or more monomers containing atleast one ethylene unsaturation in amounts ranging from 0.01% to 10% bymoles, preferably from 0.05% to 5% by moles, wherein the averageparticle sizes of the semicrystalline fluoropolymer latex range from 10to 100 nm, preferably from 10 to 60 nm. Also semycrystallinefluoropolymers wherein the latex particle sizes have the above mentionedvalue for at least 60% by weight, preferably 70% by weight of thesemicrystalline fluoropolymer, can be used.

[0012] The invention compositions are obtainable by mixing thesemicrystalline fluoropolymer latex with the fluoroelastomer latex andsubsequent coagulation. Alternatively the invention compositions can bepolymerized in the same reactor in two subsequent steps: in a first stepthe semicrystalline fluoropolymer with the mentioned nanometric sizes ispolymerized and in a second step the fluoroelastomer is polymerized. Byoperating in this way the fluoroelastomer should cover thesemicrystalline fluoropolymer latex particles, allowing to obtain a verygood dispersion of the latter in the fluoroelastomer.

[0013] The semicrystalline fluoropolymer amount inside thefluoroelastomer matrix is in the range 2%-40% by weight, preferably5-30% by weight, more preferably 10-20% by weight on the total of thepolymeric mixture.

[0014] The semicrystalline fluoropolymer particles having the abovementioned sizes are obtainable for example by a polymerization processin an aqueous microemulsion of perfluoropolyoxyalkylenes as describedfor example in the European patent application EP 99112083.3 in the nameof the Applicant, herein incorporated by reference. Microemulsionpolymerization methods can also be used, wherein the oil phase is formedby polymerizable unsaturated monomers, as described in U.S. Pat. No.5,523,346 and in U.S. Pat. No. 5,616,648.

[0015] The fluoroelastomers can be prepared by copolymerization of themonomers in aqueous emulsion, according to well known methods in theprior art, in the presence of radical initiators (for example alkalineor ammonium persulphates, perphosphates, perborates, percarbonates),optionally in combination with ferrous, cuprous or silver salts, or ofother easily oxidizable metals. In the reaction medium also surfactantsof various kind, among which the fluorinated surfactants areparticularly preferrred, are usually present.

[0016] Alternatively the fluoroelastomers can be prepared in bulk or insuspension, in an organic liquid in which a suitable radical initiatoris present, according to well known techniques.

[0017] The polymerization reaction is generally carried out attemperatures in the range 25°-150° C., under a pressure up to 10 MPa.

[0018] The fluoroelastomers are preferably prepared in microemulsion ofperfluoropolyoxyalkylens, according to U.S. Pat. No. 4,789,717 and U.S.Pat. No. 4,864,006.

[0019] The Applicant has found that in order to obtain the results ofthe present invention it is essential that the semi-crystallinefluoropolymer filler latex has the mentioned nanometric sizes, while thesize of the latex of the fluoroelastomer is not critical.

[0020] When the semi-crystalline fluorinated filler is based on modifiedPTFE, for its preparation comonomers having an ethylene unsaturationboth of hydrogenated and fluorinated type, can be used. Among thosehydrogenated, ethylene, propylene, acrylic monomers, for examplemethylmethacrylate, (meth)acrylic acid, butylacrylate,hydroxyethylhexyl-acrylate, styrene monomers can be mentioned.

[0021] Among the fluorinated comonomers we can mention:

[0022] perfluoroolefins C₃-C₈, such as hexafluoropropene (HFP),hexafluoroisobutene;

[0023] hydrogenated fluorolefins C₂-C₈, such as vinyl fluoride (VF),vinylidene fluoride (VDF), trifluoroethylene, perfluoroalkylethyleneCH₂═CH—R_(f), wherein R_(f) is a perfluoroalkyl C₁-C₆;

[0024] chloro- and/or bromo- and/or iodo-fluoroolefins C₂-C₈, such aschlorotrifluoroethylene (CTFE);

[0025] (per)fluoroalkylvinylethers (PAVE) CF₂═CFOR_(f), wherein R_(f) isa (per)fluoroalkyl C₁-C₆, for example CF₃, C₂F₅, C₃F₇;

[0026] (per)fluoro-oxyalkylvinylethers CF₂═CFOX, wherein X is:

[0027] an alkyl C₁-C₁₂, or an oxyalkyl C₁-C₁₂, or a (per)fluoro-oxyalkylC₁-C₁₂ having one or more ether groups, for exampleperfluoro-2-propoxy-propyl; fluorodioxoles, preferablyperfluorodioxoles.

[0028] PAVEs are preferred comonomers, specifically perfluoromethyl-,ethyl-, propylvinylether and fluorodioxoles, preferablyperfluorodioxoles.

[0029] The fluoroelastomers used in the present invention belong to thefollowing classes:

[0030] (1) VDF-based copolymers, wherein VDF is copolymerized with atleast one comonomer selected from the following:

[0031] perfluoroolefins C₂-C₈, such as tetrafluoroethylene (TFE),hexafluoropropene (HFP); chloro- and/or bromo- and/or iodo-fluoroolefinsC₂-C₈, such as chlorotrifluoroethylene (CTFE) andbromotrifluoroethylene; (per)fluoroalkylvinylethers (PAVE) CF₂═CFOR_(f),wherein R_(f) is a (per)-fluoroalkyl C₁-C₆, for example trifluoromethyl,bromodifluoromethyl, pentafluoropropyl; perfluorooxyalkylvinylethersCF₂═CFOX, wherein X is a perfluorooxyalkyl C₁-C₁₂ having one or moreether groups, for example perfluoro-2-propoxy-propyl; non fluorinatedolefins (Ol) C₂-C₈, for example ethylene and propylene;

[0032] (2) TFE-based copolymers, wherein TFE is copolymerized with atleast one comonomer selected from the following:

[0033] (per)fluoroalkylvinylethers (PAVE) CF₂═CFOR_(f), wherein R_(f) isas above defined; perfluoro-oxyalkylvinylethers CF₂═CFOX, wherein X isas above defined; fluoroolefins C₂-C₈ containing hydrogen and/or chloroand/or bromo and/or iodo atoms; non fluorinated olefins (Ol) C₂-C₈;perfluorovinylethers containing hydrocyanic groups as described in U.S.Pat. No. 4,281,092, U.S. Pat. No. 5,447,993, U.S. Pat. No.5,789,489.

[0034] Preferably the invention fluoroelastomers contain perfluorinatedmonomers, and preferably the base structure of these fluoroelastomers isselected from the copolymers of class (2), wherein TFE is polymerizedwith one or more perfluorinated comonomers as above mentioned.

[0035] Within the above defined classes, preferred compositions by molesof the monomers forming the base structure of the fluoroelastomer arethe following:

[0036] (a) vinylidene fluoride (VDF) 45-85%, hexa-fluoropropene (HFP)15-45%, tetrafluoroethylene (TFE) 0-30%;

[0037] (b) vinylidene fluoride (VDF) 50-80%, perfluoroalkylvinylether(PAVE) 5-50%, tetrafluoroethylene (TFE) 0-20%;

[0038] (c) vinylidene fluoride (VDF) 20-30%, non fluorinated olefins(Ol) C₂-C₈ 10-30%, hexafluoropropene (HFP) and/orperfluoroalkylvinylether (PAVE) 18-27%, tetrafluoroethylene (TFE)10-30%;

[0039] (d) tetrafluoroethylene (TFE) 50-80%, perfluoroalkylvinylether(PAVE) 20-50%;

[0040] (e) tetrafluoroethylene (TFE) 45-65%, non fluorinated olefins(Ol) C₂-C₈ 20-55%, vinylidene fluoride 0-30%;

[0041] (f) tetrafluoroethylene (TFE) 32-60% by moles, non fluorinatedolefins (Ol) C₂-C₈ 10-40%, perfluoroalkylvinylether (PAVE) 20-40%;

[0042] (g) tetrafluoroethylene (TFE) 33-75%, perfluoroalkylvinylether(PAVE) 15-45%, vinylidene fluoride (VDF) 5-30%.

[0043] Specific particularly preferred compositions are:

[0044] (d) TFE 50-80%, PAVE 20-50%;

[0045] (g) TFE 33-75%, PAVE 15-45%, VDF 5-30%.

[0046] Optionally the fluoroelastomers comprise also monomer unitsderiving from a bis-olefin having general formula:

[0047] wherein:

[0048] R₁, R₂, R₃, R₄, R₅, R₆, equal to or different from each other,are H or alkyls C₁-C₅;

[0049] Z is a linear or branched, alkylene or cycloalkylene C₁-C₁₈radical, optionally containing oxygen atoms, preferably at leastpartially fluorinated, or a (per)fluoropolyoxyalkylene radical, asdescribed in EP 661,304 in the name of the Applicant.

[0050] The unit amount in the chain deriving from said bis-olefins isgenerally in the range 0.01-1.0 by moles, preferably 0.03-0.5 by moles,still more preferably 0.05-0.2% by moles for 100 moles of the otherabove mentioned monomer units forming the fluoroelastomer basestructure.

[0051] The fluoropolymers of the present invention can be cured byperoxidic route, wherefore they preferably contain along the chainand/or in terminal position of the macromolecules iodine and/or bromineatoms. The introduction of such iodine and/or bromine atoms can beachieved by addition, in the reaction mixture, of brominated and/oriodinated cure-site comonomers, such as bromo and/or iodo olefins havingfrom 2 to 10 carbon atoms (as described for example in U.S. Pat. No.4,035,565 and U.S. Pat. No. 4,694,045), or iodo and/or bromofluoroalkylvinylethers (as described in U.S. Pat. No. 4,745,165, U.S.Pat. No. 4,564,662 and EP 199,138), in such amounts so that the contentof cure-site comonomers in the final product is generally in the range0.05-2 moles for 100 moles of the other base monomer units.

[0052] Other usable iodinated compounds are the triodinated derivingfrom triazines as described in European patent application EP 860,436and in the European patent application EP 99114823.0.

[0053] Alternatively or also in association with the cure-sitecomonomers it is possible to introduce iodine and/or bromine end atomsby addition to the reaction mixture of iodinated and/or brominated chaintransfer agents, such as for example the compounds of formulaR_(f)(I)_(x)(Br)_(y), wherein R_(f) is a (per)fluoroalkyl or a(per)fluorochloroalkyl having from 1 to 8 carbon atoms, while x and yare integers between 0 and 2, with 1≧x+y≧2 (see for example U.S. Pat.No. 4,243,770 and U.S. Pat. No. 4,943,622). It is also possible to use,as chain transfer agents, alkaline or earth-alkaline metal iodidesand/or bromides, according to U.S. Pat. No. 5,173,553.

[0054] In association with the chain transfer agents containing iodineand/or bromine, other chain transfer agents known in the prior art, suchas ethyl acetate, diethylmalonate, etc., can be used.

[0055] Curing by peroxidic route is carried out, according to knowntechniques, by addition of a suitable peroxide capable to generateradicals by thermal decomposition. Among the most commonly used wemention: dialkylperoxides, such as for example di-terbutyl-peroxide and2,5-dimethyl-2,5-di-(terbutylperoxy)hexane; dicumyl peroxide; dibenzoylperoxide; diterbutyl perbenzoate;di[1,3-dimethyl-3-(terbutylperoxy)-butyl]carbonate. Other peroxidicsystems are described, for example, in European patent applications EP136,596 and EP 410,351.

[0056] To the compound (curable blend) other products are then added,such as:

[0057] (a) curing coagents, in an amount generally in the range 0.5-10%,preferably 1-7% by weight with respect to the poly-ymer; among them,triallyl-cyanurate; triallyl-isocyanurate (TAIC);tris(diallylamine)-s-triazine; triallylphosphite;N,N-diallyl-acrylamide; N,N,N′,N′-tetraallylmalonamide;trivinyl-isoyanurate; 2,4,6-trivinyl-methyl-trisiloxane, etc., arecommonly used; TAIC is particularly preferred; other preferredcrosslinking agents are bis-olefins described in the European patentapplication

[0058] EP 769,520. Other crosslinking agents which can be used are thetriazines described in the European patent applications EP 860,436 andWO97/05122.

[0059] (b) optionally a metal compound, in an amount in the range 1-15%,preferably 2-10%, by weight with respect to the polymer, selected fromoxides or hydroxides of divalent metals, such as for example, Mg, Zn, Caor Pb, optionally associated to a weak acid salt, such as for examplestearates, benzoates, carbonates, oxalates or phosphites of Ba, Na, K,Pb, Ca;

[0060] (c) optionally acid acceptors of the non metal oxide type, suchas 1,8 bis dimethyl amino naphthalene, octadecyl-amine etc. as describedin EP 708,797.

[0061] (d) other conventional additives, such as thickening fillers,pigments, antioxidants, stabilizers and the like.

[0062] When the fluoroelastomer matrix contains cyano groups, thefluoropolymer curing of the present invention is carried out by using ascrosslinking agents tin organic compounds or di-aromatic aminiccompounds, as described in U.S. Pat. No. 4,394,489, U.S. Pat. No.5,767,204, U.S. Pat. No. 5,789,509. This type of curing can beassociated to a curing of peroxidic type, when the fluoroelastomermatrix contains iodine or bromine atoms, preferably end atoms, asdescribed in U.S. Pat. No. 5,447,993.

[0063] The present invention will be better illustrated by the followingExamples, which have a merely indicative but not limitative purpose ofthe scope of the invention itself.

EXAMPLE 1

[0064] a) Preparation of the Semicrystalline Fluoropolymer

[0065] In a 10 l autoclave, equipped with a stirrer working at 545 rpm,after evacuation, 6.5 l of demineralized water and 272 ml of aperfluoropolyoxyalkylene microemulsion were introduced: the latter waspreviously obtained by mixing:

[0066] 59 ml of a perfluoropolyoxyalkylene, having an acid end group, offormula:

CF₂ClO(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₂COOH

[0067] wherein n/m=10, having average molecular weight of 600;

[0068] 59 ml of a 30% by volume NH₄OH aqueous solution;

[0069] 118 ml of demineralized water;

[0070] 36 ml of Galden^((R)) D02 of formula:

CF₃O(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₃

[0071] wherein n/m=20, having average molecular weight of 450.

[0072] The autoclave was then heated up to 80° C. and maintained at saidtemperature for the whole reaction duration. 0.48 bar of C₂H₆ were fedinto the autoclave and the pressure was increased and maintainedconstant at 11 bar during the whole polymerization with TFE.

[0073] 6.5 g of ammonium persulphate (APS) as initiator agent were thenintroduced into the autoclave. After 37 minutes of reaction, theautoclave was cooled and the latex discharged. The latex characteristicsare reported in Table 1.

[0074] b) Preparation of the Fluoroelastomer

[0075] In a 10 l autoclave, equipped with a stirrer working at 545 rpm,after evacuation, 6.5 l of demineralized water and 67 ml of aperfluoropolyoxyalkylene microemulsion were introduced: the latter waspreviously obtained by mixing:

[0076] 14.5 ml of a perfluoropolyoxyalkylene, having an acid end group,of formula:

CF₂ClO(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₂COOH

[0077] wherein n/m=10, having average molecular weight of 600;

[0078] 14.5 ml of a 30% by volume NH₄OH aqueous solution;

[0079] 29 ml of demineralized water;

[0080] 9 ml of Galden^((R)) D02 of formula:

CF₃O(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₃

[0081] wherein n/m=20, having average molecular weight of 450.

[0082] The autoclave was then heated up to 80° C. and maintained at saidtemperature for the whole reaction duration. The following mixture ofmonomers was then fed:

[0083] perfluoromethylvinylether (PMVE) 60% by moles

[0084] tetrafluoroethylene (TFE) 40% by moles so as to increase thepressure to 25 bar.

[0085] 0.32 g of ammonium persulphate (APS) as initiator agent;

[0086] 26 g of 1,6-diiodoperfluorohexane (C₆F₁₂I₂) as chain transferagent;

[0087] 5 g of bis-olefin of formula CH₂═CH—(CF₂)₆—CH═CH₂; the additionwas carried out in 20 portions, each of 0.25 g, starting from thepolymerization beginning and for every 5% increase in the monomerconversion, were then introduced in the autclave.

[0088] The 25 bar pressure was maintained constant for the wholeduration of the polymerization by feeding a mixture formed by:

[0089] perfluoromethylvinylether (PMVE) 40% by moles

[0090] tetrafluoroethylene (TFE) 60% by moles

[0091] After 137 minutes of reaction, the autoclave was cooled and thelatex discharged. The latex properties are reported in Table 1.

[0092] c) Mixing of the Latexes—Preparation of the Final Polymer

[0093] 635.6 ml of the latex obtained in Example 1a are mixed with 1517ml of the Example 1b latex. After mixing, the latex is coagulated withan aluminum sulphate solution (6 g of Al₂(SO₄)₃ for every liter oflatex) and dried at 80° C. in an air-circulating oven for 10 hours. 500g of polymer, characterized as shown in Table 2, were obtained.

EXAMPLE 2 COMPARATIVE

[0094] a) Preparation of the Semicrystalline Fluoropolymer

[0095] In a 50 l autoclave, equipped with a stirrer working at 245 rpm,32 l of demineralized water, 12 g of ammonium prfluorooctanoate and 140g of paraffin with melting point 52-56° C. were introduced, afterevacuation.

[0096] The autoclave was then heated to 89° C. and progressivelyincreased up to 102.1° C. with a rate of 1° C. per minute for the wholereaction duration. 350 mbar of ethane were fed into the autoclave andthe pressure was increased and maintained at 20 bar by continuouslyfeeding TFE during the polymerization.

[0097] 3.5 g of ammonium prsulphate (APS) as initiator agent andsubsequently further 2 g of an APS aqueous solution at a flow-rate of 50cc/min were introduced in the autoclave.

[0098] After 73 minutes of reaction, the autoclave was cooled and thelatex discharged. The latex characteristics are reported in Table 1.

[0099] b) Preparation of the Fluoroelastomer

[0100] The fluoroelastomer latex was obtained as described in Example1b.

[0101] c) Mixing of the Latexes—Preparation of the Final Polymer

[0102] 428.5 ml of the latex obtained in Example 2a are mixed with 1517ml of the Example 2b latex. After mixing, the latex is coagulated withan aluminum sulphate solution (6 g of Al₂(SO₄)₃ for every liter oflatex) and dried at 80° C. in an air-circulating oven for 10 hours. 500g of polymer, characterized as shown in Table 2, were obtained.

EXAMPLE 3 COMPARATIVE

[0103] a) Preparation of the Semicrystalline Fluoropolymer

[0104] The PTFE latex was obtained in the presence of a microemulsion asin Example 1a. The latex was subsequently coagulated with an aluminumsulphate solution (6 g of Al₂(SO₄)₃ for each liter of latex) and driedat 150° C. in an air-circulation oven for 24 hours.

[0105] b) Preparation of the Fluoroelastomer

[0106] The perfluoroelastomer latex was obtained as described in Example1b. The latex was subsequently coagulated with an aluminum sulphatesolution (6 g of Al₂(SO₄)₃ for each liter of latex) and dried at 100° C.in an air-circulation oven for 12 hours.

[0107] c) Mechanical Mixing—Preparation of the Final Polymer

[0108] 425 g of fluoroelastomer of Example 3b were mixed with 75 g ofPTFE powder obtained from Example 3a in an open mixer with rollersheated at 60° C. In the mixing process the perfluoroelastomer isintroduced first with the rollers completely near the one to the otherand mixed until a continuous polymer film is obtained. The PTFE powderwas then added until obtaining an uniform mixing. The obtained mixturewas characterized as reported in Table 2.

EXAMPLE 4 COMPARATIVE

[0109] 425 g of fluoroelastomer obtained in Example 3b were mixed in anopen mixer with 75 g of PTFE MP 1600 by Du Pont by using the proceduredescribed in Example 3c. The mixture properties are reported in Table 2.

EXAMPLE 5

[0110] a) Preparation of the Semicrystalline Fluoropolymer

[0111] In a 50 l autoclave, equipped with a stirrer working at 245 rpm,after evacuation, 32 l of demineralized water, 140 g of a paraffin withmelting point 52°-56° C. and 300 ml of a perfluoropolyoxyalkylenemicroemulsion were introduced: the latter was previously obtained bymixing:

[0112] 65 ml of a perfluoropolyoxyalkylene, having an acid end group, offormula:

CF₂ClO(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₂COOH

[0113] wherein n/m=10, having average molecular weight of 600;

[0114] 65 ml of a 30% by volume NH₄OH aqueous solution;

[0115] 130 ml of demineralized water;

[0116] 40 ml of Galden^((R)) D02 of formula:

CF₃O(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₃

[0117] wherein n/m=20, having average molecular weight of 450.

[0118] The autoclave was then heated up to 80° C. and the temperaturewas progressively increased up to 96° C. with a rate of 0.6° C./min forthe whole reaction duration. 370 mbar of C₂H₆ were fed into theautoclave and the pressure was increased and maintained constant at 20bar during the whole polymerization by feeding TFE.

[0119] 2.5 g of ammonium persulphate (APS) as initiator agent were thenintroduced into the autoclave and subsequently by feeding, starting from10% of conversion, 0.54 g of APS every 10% of monomer conversion. After64 minutes of reaction, the autoclave was cooled and the latexdischarged. The latex characteristics are reported in Table 3.

[0120] b) Preparation of the Fluoroelastomer

[0121] The fluoroelastomer latex was obtained as described in Example1b, except that the amount of 1,6-diiodoperfluorohexane was of 30 ginstead of 26 g.

[0122] c) Mixing of the Latexes—Preparation of the Final Polymer

[0123] 347 ml of the latex obtained in Example 5a are mixed with 1197 mlof the Example 5b latex. After mixing, the latex is coagulated with analuminum sulphate solution (6 g of Al₂(SO₄)₃ for each liter of latex)and dried at 80° C. in an air-circulating oven for 10 hours. 500 g ofpolymer, characterized as shown in Table 4, were obtained.

EXAMPLE 6

[0124] In a 10 l autoclave, equipped with a stirrer working at 545 rpm,after evacuation, 6.5 l of demineralized water and 260 ml of aperfluoropolyoxyalkylene microemulsion were introduced: the latter waspreviously obtained by mixing:

[0125] 56.3 ml of a perfluoropolyoxyalkylene having an acid end group offormula:

CF₂ClO(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₂COOH

[0126] wherein n/m=10, having average molecular weight of 600;

[0127] 56.3 ml of a 30% by volume NH₄OH aqueous solution;

[0128] 112.7 ml of demineralized water;

[0129] 34.7 ml of Galden^((R)) D02 of formula:

CF₃O(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₃

[0130] wherein n/m=20, having average molecular weight of 450.

[0131] The autoclave was then heated up to 80° C. and maintained at saidtemperature for the whole reaction duration. 0.48 bar of ethane were fedinto the autoclave and the pressure was increased and maintainedconstant at 11 bar by continuously feeding TFE during thepolymerization.

[0132] 6.5 g of ammonium persulphate (APS) were then introduced into theautoclave as initiator. After 15 minutes of reaction, the autoclave wascooled, degassed and discharged. The latex characteristics are reportedin Table 3. Subsequently 2368 ml (corresponding to 449.9 g of polymer)of the latex are introduced again in the 10 liter reactor to which 4132liters of demineralized water are added. The autoclave is then broughtto 90° C. and maintained for one hour at said temperature in order todecompose all the residual initiator agent. Subsequently the temperatureis increased to 80° C. and maintained constant for the whole duration ofthe polymerization. The following mixture of monomers was then fed:

[0133] perfluoromethylvinylether (PMVE) 60% by moles

[0134] tetrafluoroethylene (TFE) 40% by moles so as to increase thepressure to 25 bar.

[0135] 0.32 g of ammonium persulphate (ADS) as initiator agent;

[0136] 22.3 g of 1,6-diiodoperfluorohexane (C₆F₁₂I₂) as chain transferagent;

[0137] 4.28 g of bis-olefin of formula CH₂═CH—(CF₂)₆—CH═CH₂; theaddition was carried out in 20 portions, each of 0.214 g, starting fromthe polymerization beginning and for every 5% increase in the monomerconversion, were then introduced in the autoclave.

[0138] The 25 bar pressure was maintained constant for the wholeduration of the polymerization by feeding a mixture formed by:

[0139] perfluoromethylvinylether (PMVE) 40% by moles

[0140] tetrafluoroethylene (TFE) 60% by moles

[0141] After 45 minutes of reaction corresponding to 2550 g ofelastomer, the autaoclave was cooled and the latex discharged. The latexis coagulated with an aluminum sulphate solution (6 g of Al₂(SO₄)₃ foreach liter of latex) and dried at 80° C. in an air-circulating oven for10 hours. The obtained polymer was characterized as shown in Table 4.

EXAMPLE 7

[0142] a) Preparation of the Semicrystalline Fluoropolymer

[0143] The PTFE latex was obtained as described in Example 5a. The latexcharacteristics are reported in Table 3.

[0144] b) Preparation of the Fluoroelastomer

[0145] The fluoroelastomer latex was obtained as described in Example5b. The characteristics are reported in Table 3.

[0146] c) Mixing of the Latexes—Preparation of the Final Polymer

[0147] 463 ml of the latex obtained in Example 7a are mixed with 1127 mlof the Example 7b latex. After mixing, the latex is coagulated with analuminum sulphate solution (6 g of Al₂(SO₄)₃ for each liter of latex)and dried at 80° C. in an air-circulating oven for 10 hours. Theobtained polymer was characterized as shown in Table 4.

EXAMPLE 8

[0148] The polymer obtained in Example 7c was crosslinked withbis-olefin of formula CH₂═CH—(CF₂)₆—CH═CH₂, instead of TAIC. Thecompound characteristics are reported in Table 4.

EXAMPLE 9

[0149] a) Preparation of the Semicrystalline Fluoropolymer

[0150] The PTFE latex was obtained as reported in Example 1a. The latexcharacteristics are reported in Table 5.

[0151] b) Preparation of the Fluoroelastomer

[0152] In a 10 l autoclave, equipped with a stirrer working at 545 rpm,6.5 l of demineralized water and 26 g of ammonium perfluorooctanoatewere introduced, after evacuation.

[0153] The autoclave was then heated up to 80° C. and maintained at saidtemperature for the whole reaction duration. The following mixture ofmonomers was then fed:

[0154] perfluoromethylvinylether (PMVE) 60% by moles

[0155] tetrafluoroethylene (TFE) 40% by moles so as to increase thepressure to 25 bar.

[0156] 6.5 g of ammonium persulphate (APS) as initiator agent;

[0157] 25 g of 1,6-diiodoperfluorohexane (C₆F₁₂I₂) as chain transferagent;

[0158] 5 g of bis-olefin of formula CH₂═CH—(CF₂)₆—CH═CH₂; the additionwas carried out in 20 portions, each of 0.25 g, starting from thepolymerization beginning and for every 5% increase in the monomerconversion, were then introduced in the autoclave.

[0159] The 25 bar pressure was maintained constant for the wholeduration of the polymerization by feeding a mixture formed by:

[0160] perfluoromethylvinylether (PMVE) 40% by moles

[0161] tetrafluoroethylene (TFE) 60% by moles

[0162] After 500 minutes of reaction, the autoclave was cooled and thelatex discharged. The latex properties are reported in Table 5.

[0163] c) Mixing of the Latexes—Preparation of the Final Polymer

[0164] 551.5 ml of the latex obtained in Example 9a are mixed with1393.5 ml of the Example 9b latex. After mixing, the latex is coagulatedwith an aluminum sulphate solution (6 g of Al₂(SO₄)₃ for each liter oflatex) and dried at 80° C. in an air-circulating oven for 10 hours. 500g of polymer, characterized as shown in Table 6, were obtained.

EXAMPLE 10

[0165] a) Preparation of the Semicrystalline Fluoropolymer

[0166] In a 10 l autoclave, equipped with a stirrer working at 545 rpm,after evacuation, 6.5 l of demineralized water and 65.1 ml of aperfluoropolyoxyalkylene microemulsion were introduced: the latter waspreviously obtained by mixing:

[0167] 14.1 ml of a perfluoropolyoxyalkylene, having an acid end group,of formula:

CF₂ClO(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₂COOH

[0168] wherein n/m=10, having average molecular weight of 600;

[0169] 14.1 ml of a 30% by volume NH₄OH aqueous solution;

[0170] 28.2 ml of demineralized water;

[0171] 8.7 ml of Galden^((R)) D02 of formula:

CF₃O(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₃

[0172] wherein n/m=20, having average molecular weight of 450.

[0173] The autoclave was then heated up to 80° C. and maintained at saidtemperature for the whole reaction duration. The autoclave waspressurized to the pressure of 0.56 bar with ethane and then to thepressure of 25 bar with a monomer mixture constituted by 10% by moles ofperfluoromethylvinylether (PMVE) and 90% by moles of tetrafluoroethylene(TFE).

[0174] 1.3 g of ammonium persulphate (APS) as initiator agent were thenintroduced in the autoclave. During the reaction the pressure ismaintained at 25 bar by continuously feeding the following monomermixture: 3.5% by moles of PMVE and 96.5% of TFE.

[0175] After 60 minutes of reaction, the autoclave was cooled and thelatex discharged. The latex characteristics are reported in Table 7.

[0176] b) Preparation of the Fluoroelastomer

[0177] In a 22 l autoclave, equipped with a stirrer working at 460 rpm,after evacuation, 15 l of demineralized water and 154.5 ml of aperfluoropolyoxyalkylene microemulsion were introduced: the latter waspreviously obtained by mixing:

[0178] 33.46 ml of a perfluoropolyoxyalkylene, having an acid end group,of formula:

CF₂ClO(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₂COOH

[0179] wherein n/m=10, having average molecular weight of 600;

[0180] 33.46 ml of a 30% by volume NH₄OH aqueous solution;

[0181] 66.93 ml of demineralized water;

[0182] 20.65 ml of Galden^((R)) D02 of formula:

CF₃O(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₃

[0183] wherein n/m=20, having average molecular weight of 450.

[0184] The autoclave was then heated up to 80° C. and maintained at saidtemperature for the whole reaction duration. The following mixture ofmonomers was then fed:

[0185] perfluoromethylvinylether (PMVE) 60% by moles

[0186] tetrafluoroethylene (TFE) 40% by moles so as to increase thepressure to 25 bar.

[0187] 0.75 g of ammonium persulphate (APS) as initiator agent;

[0188] 69.24 g of 1,6-diiodoperfluorohexane (C₆F₁₂I₂) as chain transferagent;

[0189] 11.09 g of bis-olefin of formula CH₂═CH—(CF₂)₆—CH═CH₂; theaddition was made in 20 portions, each of 0.554 g, starting from thepolymerization beginning and for every 5% increase in the monomerconversion, were then introduced in the autoclave.

[0190] The 25 bar pressure was maintained constant for the wholeduration of the polymerization by feeding a mixture formed by:

[0191] perfluoromethylvinylether (PMVE) 40% by moles

[0192] tetrafluoroethylene (TFE) 60% by moles

[0193] After 110 minutes of reaction, the autoclave was cooled and thelatex discharged. The latex properties are reported in Table 7.

[0194] c) Mixing of the Latexes—Preparation of the Final Polymer

[0195] 238 ml of the latex obtained in Example 10a are mixed with 1187ml of the Example 10b latex. After mixing, the latex is coagulated withan aluminum sulphate solution (6 g of Al₂(SO₄)₃ for each liter of latex)and dried at 80° C. in an air-circulating oven for 10 hours. 500 g ofpolymer, characterized as shown in Table 8, were obtained.

EXAMPLE 11

[0196] In a 5 l autoclave, equipped with stirrer working at 630 rpm,after evacuation, 3.5 l of demineralized water and 35 ml of aperfluoropolyoxyalkylene microemulsion were introduced: the latter waspreviously obtained by mixing:

[0197] 7.58 ml of a perfluoropolyoxyalkylene, having an acid end group,of formula:

CF₂ClO(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₂COOH

[0198] wherein n/m=10, having average molecular weight of 600;

[0199] 7.58 ml of a 30% by volume NH₄OH aqueous solution;

[0200] 15.16 ml of demineralized water;

[0201] 4.68 ml of Galden^((R)) D02 of formula:

CF₃O(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₃

[0202] wherein n/m=20, having average molecular weight of 450.

[0203] The autoclave was then heated up to 80° C. and maintained at saidtemperature for the whole reaction duration. The autoclave waspressurized to the pressure of 0.56 bar with ethane and then to thepressure of 25 bar with a monomer mixture formed by 10% by moles ofperfluoromethylvinylether (PMVE) and 90% by moles of tetrafluoroethylene(TFE).

[0204] In the autoclave 0.7 g of ammonium persulphate (APS) as initiatoragent were then introduced. During the reaction the pressure ismaintained at 25 bar by continuously feeding the following monomermixture: 3.5% by moles of PMVE and 96.5% of TFE.

[0205] After 10 minutes of reaction, the autoclave was cooled, degassedand discharged. The latex characteristics are reported in Table 7.Subsequently 747 ml (corresponding to 225 g of polymer) of the latex areintroduced again in the 5 liters reactor to which 2.703 liters ofdemineralized water are added. The autoclave is then heated up to 90° C.and maintained for one hour at said temperature in order to decomposeall the residual initiator agent. Subsequently the temperature isbrought to 80° C. and maintained constant for the whole duration of thepolymerization. The following mixture of monomers was then fed:

[0206] perfluoromethylvinylether (PMVE) 60% by moles

[0207] tetrafluoroethylene (TFE) 40% by moles so as to increase thepressure to 25 bar.

[0208] 0.175 g of ammonium persulphate (APS) as initiator agent;

[0209] 11.14 g of 1,6-diiodoperfluorohexane (C₆F₁₂I₂) as chain transferagent;

[0210] 2.14 g of bis-olefin of formula CH₂═CH—(CF₂)₆—CH═CH₂; theaddition was carried out in 20 portions, each of 0.107 g, starting fromthe polymerization beginning and for every 5% increase in the monomerconversion, were then introduced in the autoclave.

[0211] The 25 bar pressure was maintained constant for the wholeduration of the polymerization by feeding a mixture formed by:

[0212] perfluoromethylvinylether (PMVE) 40% by moles

[0213] tetrafluoroethylene (TFE) 60% by moles

[0214] After 95 minutes of reaction corresponding to 1275 g of producedelastomer, the autoclave was cooled and the latex discharged.

[0215] The latex is coagulated with an aluminum sulphate solution (6 gof Al₂(SO₄)₃ for each liter of latex) and dried at 80° C. in anair-circulating oven for 10 hours. The obtained polymer wascharacterized as shown in Table 8.

EXAMPLE 12 COMPARATIVE

[0216] a) Preparation of the Semicrystalline Fluoropolymer

[0217] In a 10 l autoclave, equipped with a stirrer working at 545 rpm,after evacuation, 6.5 l of demineralized water and 16.25 ml of aperfluoropolyoxyalkylene microemulsion were introduced: the latter waspreviously obtained by mixing:

[0218] 3.52 ml of a perfluoropolyoxyalkylene, having an acid end group,of formula:

CF₂ClO(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₂COOH

[0219] wherein n/m=10, having average molecular weight of 600;

[0220] 3.52 ml of a 30% by volume NH₄OH aqueous solution;

[0221] 7.04 ml of demineralized water;

[0222] 2.17 ml of Galden^((R)) D02 of formula:

CF₃O(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₃

[0223] wherein n/m=20, having average molecular weight of 450.

[0224] The autoclave was then heated up to 80° C. and maintained at saidtemperature for the whole reaction duration. The autoclave waspressurized to the pressure of 0.56 bar with ethane and then to thepressure or 25 bar with a monomer mixture formed by 10% by moles ofperfluoromethylvinylether (PMVE) and 90% by moles of tetrafluoroethylene(TFE).

[0225] In the autoclave 1.3 g of ammonium persulphate (APS) as initiatoragent were then introduced.

[0226] During the reaction the pressure is maintained at 25 bar bycontinuously feeding the following monomer mixture: 3.5% by moles ofPMVE and 96.5% of TFE.

[0227] After 65 minutes of reaction, the autoclave was cooled and thelatex discharged. The latex characteristics are reported in Table 7.

[0228] b) Preparation of the Fluoroelastomer

[0229] The perfluoroelastomer latex was obtained as reported in Example10b. The latex characteristics are reported in Table 7.

[0230] c) Mixing of the Latexes—Preparation of the Final Polymer

[0231] 233.7 ml of the latex obtained in Example 12a are mixed with 1187ml of the Example 12b latex. After mixing, the latex is coagulated withan aluminum sulphate solution (6 g of Al₂(SO₄)₃ for each liter of latex)and dried at 80° C. in an air-circulating oven for 10 hours. 500 g ofpolymer, characterized as shown in Table 8, were obtained.

EXAMPLE 13

[0232] a) Preparation of the Semicrystalline Fluoropolymer

[0233] The PTFE latex is obtained as reported in Example 9a. The latexproperties are reported in Table 9.

[0234] b) Preparation of the Fluoroelastomer

[0235] In a 10 l autoclave, equipped with stirrer working at 545 rpm,after evacuation, 6.5 l of demineralized water and 65.1 ml of aperfluoropolyoxyalkylene microemulsion were introduced: the latter waspreviously obtained by mixing:

[0236] 14.1 ml of a perfluoropolyoxyalkylene, having an acid end groupof formula:

CF₂ClO(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₂COOH

[0237] wherein n/m=10, having average molecular weight of 600;

[0238] 14.1 ml of a 30% by volume NH₄OH aqueous solution;

[0239] 28.2 ml of demineralized water;

[0240] 8.7 ml of Galden^((R)) D02 of formula:

CF₃O(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₃

[0241] wherein n/m=20, having average molecular weight of 450.

[0242] The autoclave was then heated up to 80° C. and maintained at saidtemperature for the whole reaction duration. The following mixture ofmonomers was then fed:

[0243] vinylidene fluoride (VDF) 28% by moles

[0244] tetrafluoroethylene (TFE) 15% by moles

[0245] hexafluoropropene (HFP) 57% by moles so as to increase thepressure to 30 bar.

[0246] 1.3 g of ammonium persulphate (APS) as initiator agent;

[0247] 16.17 g of diiodomethane (CH₂I₂) as chain transfer agent fed withthe following procedure: 20% at the reaction beginning, 40% when theconversion is equal to 20% and 40% when the conversion is equal to 80%;

[0248] 9 g of bis-olefin of formula CH₂═CH—(CF₂)₆—CH═CH₂; the additionwas made in 20 portions, each of 0.45 g, starting from thepolymerization beginning and for every 5% increase in the monomerconversion, were then introduced in the autclave.

[0249] The 30 bar pressure was maintained constant for the wholeduration of the polymerization by feeding a mixture formed by:

[0250] vinylidene fluoride (VDF) 50% by moles

[0251] tetrafluoroethylene (TFE) 25% by moles

[0252] hexafluoropropene (HFP) 25% by moles

[0253] After 270 minutes of reaction, the autoclave was cooled and thelatex discharged. The latex properties are reported in Table 9.

[0254] c) Mixing of the Latexes—Preparation of the Final Polymer

[0255] 552 ml of the latex obtained in Example 14a are mixed with 1412ml of the Example 14b latex. After mixing, the latex is coagulated withan aluminum sulphate solution (6 g of Al₂(SO₄)₃ for each liter of latex)and dried at 80° C. in an air-circulating oven for 10 hours. 500 g ofpolymer, characterized as shown in Table 10, were obtained.

EXAMPLE 14

[0256] a) Preparation of the Semicrystalline Fluoropolymer

[0257] In a 10 l autoclave, equipped with a stirrer working at 545 rpm,after evacuation, 6.5 l of demineralized water and 130 ml of aperfluoropolyoxyalkylene microemulsion were introduced: the latter waspreviously obtained by mixing:

[0258] 28.15 ml of a perfluoropolyoxyalkylene, having an acid end group,of formula:

CF₂ClO(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₂COOH

[0259] wherein n/m=10, having average molecular weight of 600;

[0260] 28.15 ml of a 30% by volume NH₄OH aqueous solution;

[0261] 56.3 ml of demineralized water;

[0262] 17.4 ml of Galden^((R)) D02 of formula:

CF₃O(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₃

[0263] wherein n/m=20, having average molecular weight of 450.

[0264] The autoclave was then heated up to 80° C. and maintained at saidtemperature for the whole reaction duration. The autoclave waspressurized to the pressure of 0.56 bar with ethane and then to thepressure of 20 bar by feeding a monomer mixture formed by 1,8% by molesof perfluoropropylvinylether (PPVE) and 98,2% by moles oftetrafluoroethylene (TFE).

[0265] In the autoclave 1.3 g of ammonium persulphate (APS) were thenintroduced as initiator. During the reaction the pressure is maintainedat 20 bar by continuously feeding the following monomer mixture: 1.8% ofPPVE and 98.2% of TFE.

[0266] After 18 minutes of reaction, the autoclave was cooled and thelatex discharged. The latex characteristics are reported in Table 9.

[0267] b) Preparation of the Fluoroelastomer

[0268] In a 10 l autoclave, equipped with a stirrer working at 545 rpm,after evacuation, 6.5 l of demineralized water and 65.1 ml of aperfluoropolyoxyalkylene microemulsion were introduced: the latter waspreviously obtained by mixing:

[0269] 14.1 ml of a perfluoropolyoxyalkylene, having an acid end group,of formula:

CF₂ClO(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₂COOH

[0270] wherein n/m=10, having average molecular weight of 600;

[0271] 14.1 ml of a 30% by volume NH₄OH aqueous solution;

[0272] 28.2 ml of demineralized water;

[0273] 8.7 ml of Galden^((R)) D02 of formula:

CF₃O(CF₂—CF(CF₃)O)_(n)(CF₂O)_(m)CF₃

[0274] wherein n/m=20, having average molecular weight of 450.

[0275] The autoclave was then heated up to 80° C. and maintained at saidtemperature for the whole reaction duration. The following mixture ofmonomers was then fed:

[0276] perfluoromethylvinylether (PMVE) 60% by moles

[0277] tetrafluoroethylene (TFE) 40% by moles so as to increase thepressure to 25 bar.

[0278] 0.32 g of ammonium persulphate (APS) as initiator agent;

[0279] 17 g of 1,6-diiodoperfluorohexane (C₆F₁₂I₂) as chain transferagent;

[0280] 5 g of bis-olefin of formula CH₂═CH—(CF₂)₆—CH═CH₂; the additionwas effected in 20 portions, each of 0.25 g, starting from thepolymerization beginning and for every 5% increase in the monomerconversion, were then introduced in the autoclave.

[0281] The 25 bar pressure was maintained constant for the wholeduration of the polymerization by feeding a mixture formed by:

[0282] perfluoromethylvinylether (PMVE) 40% by moles

[0283] tetrafluoroethylene (TFE) 60% by moles

[0284] After 80 minutes of reaction, the autoclave was cooled and thelatex discharged. The latex properties are reported in Table 9.

[0285] c) Mixing of the Latexes—Preparation of the Final Polymer

[0286] 528 ml of the latex obtained in Example 15a are mixed with 1218ml of the Example 15b latex. After mixing, the latex is coagulated withan aluminum sulphate solution (6 g of Al₂(SO₄)₃ for each liter of latex)and dried at 80° C. in an air-circulating oven for 10 hours. 500 g ofpolymer, characterized as shown in Table 10, were obtained. TABLE 1Latex con- Particle MFI⁽¹⁾ Mooney centration diameter ASTM (1 +10)^(121° C.) (g/l) (nm) D 1238 ASTM D 1646 Example 1a 118 12 82.7 —Example 1b 280 54 — 27 Example 2a 175 197 0.2 — (comp.) Example 2b 28054 — 27 (comp.)

[0287] TABLE 2 EXAMPLE Ex. 2c Ex. 3c Ex. 4 Ex. 1c comp. comp. comp. % byweight of plastomer 15 15 15 15 ML (1 + 10)^(121° C.) (ASTM D 1646) 58nd 27 — Formulation: Elastomer (phr) 100 100 100 100 TAIC (phr) 1.5 1.51.5 1.5 Luperco (phr) 2 2 2 2 ZnO (phr) 5 5 5 5 ODR (177° C., 12′ arc3°) (ASTM D 2084-81): ML Lbf. in. 11 nd 17 13 MH Lbf. in. 118 nd 115 140Ts2 sec 45 nd 45 51 T′ 90 sec 99 nd 90 109 Molding in press at 180° C.for 10 min: Sheet surface smooth nd rough rough Mechanical propertiesafter post cure at 200° C. for 1 hour (ASTM D 412-83): M100 Mpa 4.9 nd10.1 6.3 C.R. Mpa 19.3 nd 18.5 18.7 A.R. % 174 nd 145 174 ShA Hardnesspoints 69 nd 85 76 Compression set on O-ring (ASTM D 395): 200° C. for70 hours (%) 29 nd 40 broken 230° C. for 70 hours (%) 47 nd broken —

[0288] TABLE 3 Latex con- Particle MFI⁽¹⁾ Mooney centration diameterASTM (1 + 10)^(121° C.) (g/l) (nm) D 1238 ASTM D 1646 Example 5a 216 902 — Example 5b 355 60 — 20 Example 6 190 50 54.1 — Example 7a 216 90 2 —Example 7b 355 60 — 18

[0289] TABLE 4 EXAMPLE Ex. 5c Ex. 6 Ex. 7c Ex. 8 % by weight ofplastomer 15 15 20 20 ML (1 + 10)^(121° C.) (ASTM D 1646) 35 39 41 35Formulation: Elastomer (phr) 100 100 100 100 TAIC (phr) 1.5 1.5 1.5 —BO⁽²⁾ — — — 4 Luperco (phr) 2 2 2 4 ZnO (phr) 5 5 5 5 ODR (177° C., 12′arc 3°) (ASTM D 2084-81): ML Lbf. in. 8 6 12 4 MH Lbf. in. 131 108 13377 Ts2 sec 45 52 60 78 T′ 90 sec 285 138 123 330 Molding in press at180° C. for 10 min: Sheet surface smooth smooth smooth smooth Mechanicalproperties after post cure at 200° C. for 1 h (ASTM D 412-83): M100 Mpa5.6 4.5 7.9 10.1 C.R. Mpa 16.4 16.9 18.4 18.5 A.R. % 164 190 154 145 ShAHardness points 73 72 78 85 Compression set on O-ring (ASTM D 395): 200°C. for 70 hours (%) 28 49 33 43

[0290] TABLE 5 Latex con- Particle MFI Mooney centration diameter ASTM(1 + 10)^(121° C.) (g/l) (nm) D 1238 ASTM D 1646 Example 9a 136 1282.7⁽¹⁾ — Example 9b 305 163 — 38

[0291] TABLE 6 EXAMPLE Ex. 9c % by weight of plastomer 15 ML (1 +10)^(121° C.) (ASTM D 1646) 48 Formulation: Elastomer (phr) 100 TAIC(phr) 1.5 Luperco (phr) 2 ZnO (phr) 5 ODR (177° C., 12′ arc 3°) (ASTM D2084-81): ML Lbf. in. 11 MH Lbf. in. 95 Ts2 sec 48 T′ 90 sec 103 Moldingin press at 180° C. for 10 min: Sheet surface smooth Mechanicalproperties after post cure at 200° C. for 1 hour (ASTM D 412-83): M100Mpa 6.3 C.R. Mpa 22.2 A.R. % 184 ShA hardness points 73 Compession seton O-ring (ASTM D 395): 200° C. for 70 hours (%) 47

[0292] TABLE 7 Latex con- Particle MFI Mooney centration diameter ASTM(1 + 10)^(121° C.) (g/l) (nm) D 1238 ASTM D 1646 Example 10a 315 60295⁽¹⁾ — Example 10b 358 54 — 15 Example 11 301 26 216⁽²⁾ — Ex. 12acomp. 321 103 245⁽¹⁾ — Ex. 12b comp. 358 54 — 15

[0293] TABLE 8 EXAMPLE Ex. 12c Ex. 10c Ex. 11 comp. % by weight ofplastomer 15 15 15 ML (1 + 10)^(121° C.) (ASTM D 1646) 27 55 28Formulation: Elastomer (phr) 100 100 100 TAIC (phr) 1.5 1.5 1.5 Luperco(phr) 2 2 2 ZnO (phr) 5 5 5 ODR (177° C., 12′ arc 3°) (ASTM D 2084-81):ML Lbf. in. 5 20 5 MH Lbf. in. 129 134 83 Ts2 sec 54 46 54 T′ 90 sec 11497 99 Molding in press at 180° C. for 10 min: Sheet surface smoothsmooth rough Mechanical properties after post cure at 200° C. for 1 hour(ASTM D 412-83): M100 Mpa 5.7 7.1 6.6 C.R. Mpa 16.4 19.0 18.4 A.R. % 175183 177 ShA hardness points 70 79 73 Compression set on O-ring (ASTM D395): 200° C. for 70 hours (%) 29 47 —

[0294] TABLE 9 Latex con- Particle MFI Mooney centration diameter ASTM(1 + 10)^(121° C.) (g/l) (nm) D 1238 ASTM D 1646 Example 13a 136 1229.1⁽¹⁾ — Example 13b 301 72 — 51 Example 14a 142 60   80⁽²⁾ — Example14b 349 54 — 68

[0295] TABLE 10 EXAMPLE Ex. 13c Ex. 14c % by weight of plastomer 15 15ML (1 + 10)^(121° C.) (ASTM D 1646) 73 73 Formulation: Elastomer (phr)100 100 TAIC (phr) 3 1.5 Luperco (phr) 4 2 ZnO (phr) 5 5 ODR (177° C.,12′ arc 3°) (ASTM D 2084-81): ML Lbf. in. 12 30 MH Lbf. in. 96 130 Ts2sec 55 55 T′ 90 sec 115 118 Molding in press at 180° C. for 10 min:Sheete surface smooth smooth Mechanical properties after post cure at200° C. for 1 hour (ASTM D 412-83): M100 Mpa 4 6.2 C.R. Mpa 16.5 15.0A.R. % 344 164 ShA hardness points 65 73 Compression set on O-ring (ASTMD 395): 200° C. for 70 hours (%) — 32

1. Fluoropolymers comprising a fluoroelastomer matrix incorporatingtherein particles of a semicrystalline fluoropolymer latex formed bytetrafluoroethylene (TFE) homopolymers, or TFE copolymers with one ormore monomers containing at least one unsaturation of ethylene type inamounts ranging from 0.01% to 10% by moles, preferably from 0.05% to 5%by moles, wherein the average particle sizes of the semicrystallinefluoropolymer latex range from 10 to 100 nm for at least 60% by weightof the semicrystalline fluoropolymer.
 2. Fluoropolymers according toclaim 1 wherein the latex particle sizes of the semicrystallinefluoropolymer range from 10 to 60 nm.
 3. Fluoropolymers according toclaims 1-2 obtainable by mixing the semicrystalline fluoropolymer latexwith the fluoroelastomer latex and subsequent coagulation. 4.Fluoropolymers according to claimns 1-2 obtainable by polymerizing in afirst step the semicrystalline fluoropolymer and in a second step thefluoroelastomer.
 5. Fluoropolymers according to claims 1-4 wherein thesemicrystalline fluoropolymer amount inside the fluoroelastomer matrixis in the range 2%-40% by weight on the total of the polymeric mixture.6. Fluoropolymers according to claim 5 wherein the semicrystallinefluoropolymer amount inside the fluoroelastomer matrix is in the range5-30% by weight on the total of the polymeric mixture.
 7. Fluoropolymersaccording to claims 1-6 wherein the semicrystalline polymer is based onPTFE modified with comonomers with ethylene unsaturation both ofhydrogenated and fluorinated type.
 8. Fluoropolymers according to claim7 wherein the hydrogenated comonomers are selected from ethylene,propylene, methylmethacrylate, methacrylic acid, butylacrylate,hydroxyethylhexylacrylate, styrene.
 9. Fluoropolymers according to claim7 wherein the fluorinated comonomers are selected from: perfluoroolefinsC₃-C₈, such as hexafluoropropene (HFP), hexafluoroisobutene;hydrogenated fluorolefins C₂-C₈, such as vinyl fluoride (VF), vinylidenefluoride (VDF), trifluoroethylene, perfluoroalkylethylene CH₂═CH—R_(f),wherein R_(f) is a perfluoroalkyl C₁-C₆; chloro- and/or bromo- and/oriodo-fluoroolefins C₂-C₈, such as chlorotrifluoroethylene (CTFE);(per)fluoroalkylvinylethers (PAVE) CF₂═CFOR_(f), wherein R_(f) is a(per)fluoroalkyl C₁-C₆, for example CF₃, C₂F₅, C₃F₇;(per)fluoro-oxyalkyvinylethers CF₂═CFOX, wherein X is: an alkyl C₁-C₁₂,or an oxyalkyl C₁-C₁₂, or a (per)fluoro-oxyalkyl C₁-C₁₂ having one ormore ether groups, for example perfluoro-2-propoxy-propyl;fluorodioxoles.
 10. Fluoropolymers according to claims 7-9 wherein thepreferred comonomers are perfluoromethyl-, ethyl-, propylvinylether andperfluorodioxoles.
 11. Fluoropolymers according to claims 1-10 whereinthe fluoroelastomer is selected from the following classes: (1)vinylidene fluoride (VDF)-based copolymers, wherein VDF is copolymerizedwith at least one comonomer selected from the following ones:perfluoroolefins C₂-C₈, such as tetrafluoroethylene (TFE),hexafluoropropene (HFP); chloro- and/or bromo- and/or iodo-fluoroolefinsC₂-C₈, such as chlorotrifluoroethylene (CTFE) andbromotrifluoroethylene; (per)fluoroalkylvinylethers (PAVE) CF₂═CFOR_(f),wherein R_(f) is a (per)-fluoroalkyl C₁-C₆, for example trifluoromethyl,bromodifluoromethyl, pentafluoropropyl; perfluoro-oxyalkylvinylethersCF₂═CFOX, wherein X is a perfluoro-oxyalkyl C₁-C₁₂ having one or moreether groups, for example perfluoro-2-propoxy-propyl; non fluorinatedolefins (Ol) C₂-C₈, for example ethylene and propylene; (2)tetrafluoroethylene (TFE)-based copolymers, wherein TFE is copolymerizedwith at least one comonomer selected from the following:(per)fluoroalkylvinylethers (PAVE) CF₂═CFOR_(f), wherein R_(f) is asabove defined; perfluoro-oxyalkylvinylethers CF₂═CFOX, wherein X is asabove defined; fluoroolefins C₂-C₈ containing hydrogen and/or chlorineand/or bromine and/or iodine atoms; non fluorinated olefins (Ol) C₂-C₈;perfluorovinylethers containing hydrocyanic groups.
 12. Fluoropolymersaccording to claim 11 wherein the preferred fluoroelastomer is selectedfrom the following compositions expressed by moles: (a) vinylidenefluoride (VDF) 45-85%, hexafluoropropene (HFP) 15-45%,tetrafluoroethylene (TFE) 0-30%; (b) vinylidene fluoride (VDF) 50-80%,perfluoroalkylvinylether (PAVE) 5-50%, tetrafluoroethylene (TFE) 0-20%;(c) vinylidene fluoride (VDF) 20-30%, non fluorinated olefins (Ol) C₂-C₈10-30%, hexafluoropropene (HFP) and/or perfluoroalkylvinylether (PAVE)18-27%, tetrafluoroethylene (TFE) 10-30%; (d) tetrafluoroethylene (TFE)50-80%, perfluoroalkylvinylether (PAVE) 20-50%; (e) tetrafluoroethylene(TFE) 45-65%, non fluorinated olefins (Ol) C₂-C₈ 20-55%, vinylidenefluoride 0-30%; (f) tetrafluoroethylene (TFE) 32-60% by moles, nonfluorinated olefins (Ol) C₂-C₈ 10-40%, perfluoroalkylvinylether (PAVE)20-40%; (g) tetrafluoroethylene (TFE) 33-75%, perfluoroalkylvinylether(PAVE) 15-45%, vinylidene fluoride (VDF) 5-30%.
 13. Fluoropolymersaccording to claims 1-12 wherein the fluoroelastomer comprises alsomonomer units deriving from a bis-olefin having general formula:

wherein: R₁, R₂, R₃, R₄ , R₅, R₆, equal to or different from each other,are H or alkyls C₁-C₅; Z is a linear or branched, alkylene orcycloalkylene C₁-C₁₈ radical, optionally containing oxygen atoms,preferably at least partially fluorinated, or a(per)fluoropolyoxyalkylene radical.
 14. Fluoropolymers according toclaim 13 wherein the unit amount in the chain deriving from thebis-olefin is in the range 0.01-1.0% by moles of the other monomer unitsforming the fluoroelastomer base structure.
 15. Fluoropolymers accordingto claims 1-14 wherein the fluoroelastomers are cured by peroxidicroute.
 16. Fluoropolymers according to claims 1-14 wherein thefluoroelastomers when they contain cyano groups are cured by tin organiccompounds and/or di-aromatic aminic compounds.
 17. Fluoropolymersaccording to claim 16 wherein the fluoroelastomers are cured by tinorganic compounds and/or di-aromatic aminic compounds and optionally byperoxidic route if in the polymeric chair iodine and/or bromine atomsare present.
 18. Use of fluoropolymers according to claims 1-17 for thepreparation of sealing manufactured articles.